where \(Q\)  (\(p\) ) is the 4-momentum of the initial (final) baryon, \(u(Q)\)  is the Dirac spinor, \(u^\mu (p)\)  is the Rarita-Schwinger vector-spinor, such that \(p_\mu u^\mu (p)=0\)  and \(\gamma _\mu u^\mu (p)=0\)  (see, e.g. [1]}, sec. 31), and \(\varphi _K\)  is wave function of the kaon.
